Some of the compounds derived from hydrogen cyanide are known as useful starting materials for the manufacture of pharmaceutical and/or agricultural intermediates. For example, cyanogen (CN).sub.2, a dimer of hydrogen cyanide, 2minomalononitrile H.sub.2 NCH(CN).sub.2, a posturated trimer, tetramer such as diaminomaleonitrile H.sub.2 N(CN)C.dbd.C(CN)NH.sub.2 and diiminosuccinonitrile. ##STR2##
Of these compounds, 2-aminomalononitrile is too unstable to be isolated from polymerization of hydrogen cyanide. Generally it is prepared by other tedius method and exists as p-toluenesulfonate, which also is so unstable that it undergoes decomposition and discoloration. Moreover, it is too expensive to be used as industrial materials.
It is well know that hydrogen cyanide polymerizes easily in the presence of catalytic amount of a base to give undesired polymers unless the reaction conditions are well controlled, Usually, by controlling reaction conditions, hydrogen cyanide can be tetramized to give diaminomaleonitrile.
Actually, we have already disclosed in the United Kingdom Patent specication No. 1472439 that an efficient process for the production of diaminomaleonitrile which comprises tetramerizing hydrogen cyanide in liquid phase in the presence of a base catalyst such as triethylamine and a cocatalyst such as diphenyl disulfide at a temperature of 45.degree.-7020 C. This fact suggests that a basic catalyst may be the polymerization initiator and a disulfide may be the polymerization regulator.
An object of the invention is to provide 2,3-diaminoacrylonitrile derivatives, a new and stable trimer of hydrogen cyanide, which similar to 2-aminomalononitrile, can be used as starting materials for the preparation of a wide variety of organic compounds.
A further of the present invention is to provide the method of producing these derivatives at a moderate price.